Based on the poor performance of fourth grade students on national and international tests of mathematics, it is evident students in the early grades are not adequately prepared in mathematics. Several researchers have demonstrated that students who complete kindergarten with an inadequate knowledge of basic mathematics concepts and skills will continue to experience difficulties with mathematics throughout their elementary and secondary years. There is a critical need for early identification of students who are experiencing difficulties in mathematics and, then, to provide immediate and targeted instruction in order to remediate these deficits. Four domains are important to building a strong foundation in mathematics: topics within number, solving problems focusing on relationships, understanding measurement, and working with spatial concepts. However, most screeners and diagnostic instruments for early identification of mathematics deficiencies only address the concept of number. As a result, the information provided to teachers for remediation is inadequate and incomplete. This project will develop a web-based two stage assessment system: the Primary Screener for Mathematics (PSM), a tool for quickly identifying students with mathematics deficiencies, and the Primary Mathematics Assessment (PMA), a more comprehensive targeted assessment, which will provide a more in- depth profile of specific deficits and lead to better instructional recommendations. The information provided by the PSM and PMA will be used to develop a more comprehensive remediation program for K-2 students struggling in mathematics. This web-based PSM and PMA assessment system will provide immediate feedback, which will result in more timely and comprehensive remedial interventions. The proposed research will focus on refining and validating a web-based PSM and PMA. Additional items will be assessed and tested to determine their reliability and psychometric properties. Potential items for the PSM and PMA will be assessed by evaluating the measures with 100 students in each of three grade levels (K-2) using a beta version of the PSM. After the PSM and PMA items are developed they will be integrated to a beta web-based PMA system that will be evaluated with an additional 300 K-2 students. In Phase II, the assessment system will be evaluated for predictive and concurrent validly and a full set of mathematics instructions and lesson plans will be created to assist teachers in teaching remedial skills. The screening measure (PSM) and the more extensive diagnostic measure (PMA) will be evaluated for test-retest reliability and for concurrent and predictive validity.